A former linebacker for the Denver Broncos has sued Greenberg Traurig, alleging that the law firm was getting a secret 7 percent commission for steering investors to a thoroughbred breeding-rights leasing program at the same time that it advised him and his wife about the appropriateness of the tax shelter.

Bill Romanowski says he and his wife put $1.3 million into the ClassicStar program and wound up with Internal Revenue Service audits of their tax returns rather than the write-offs they had expected, reports the Denver Post.

His lawsuit was filed Friday in federal court in Denver.

The law firm didn’t respond to requests for comment yesterday from the newspaper.